I have a 97 Lumina just had the intake manifold done by a buddy, after he finally got the spark plug wires right, it seemed ok. Then it started idling super high. Checked the throttle cables all seemed ok. Took it on the freeway and noticed very bad acceleration, though the car would stay at speed without my foot on the gas. Could this be egr sensor or oxg. sensor? Tried to check the vacume lines as best I could does'nt seem to be anything wrong there? Help, any ideas?